The report describes a project to simulate vehicle impact tests using an impact sled facility. The kinetic energy of the sled must be absorbed in a controlled manner, and steel tube crushed axially is one method often used for this purpose. By using several ranks of tubes of different lengths and diameters, an attempt may be made to simulate the deceleration pulse of any particular model of car. The first phase of the present project investigates current practice in this field and considers the basic behaviour of axially crushed tube, including crumpling pattern, crumpling load, impact velocity dependence and the effect of variations in tube dimensions and material properties. Consideration is also given to rebound effects originating in the storage of elastic energy in the plastically formed folds. Nomograms are developed for the rapid estimation of the number and dimensions of the tubes in each rank. Also the repeatability of identical sled runs is compared with the repeatability of runs made with identical vehicles. Recommendations are made for continuation of this project, with the main emphasis on further development of the simulation of the rebound energy of vehicles under impact.
Abstract